This is the third paper of a series devoted to the study of the global properties of Joguet’s sample of 79 nearby galaxies observable from the southern hemisphere, of which 65 are Seyfert 2 galaxies. We use the population synthesis models of Paper II to derive ‘pure’ emission-line spectra for the Seyfert 2 galaxies in the sample, and thus explore the statistical properties of the nuclear nebular components and their relation to the stellar populations. We find that the emission-line clouds suffer substantially more extinction than the starlight, and we confirm the correlations between stellar and nebular velocity dispersions and between emission-line luminosity and velocity dispersions, although with substantial scatter. Nuclear luminosities correlate with stellar velocity dispersions, but Seyferts with conspicuous star-forming activity deviate systematically towards higher luminosities. Removing the contribution of young stars to the optical continuum produces a tighter and steeper relation, L ∝ σ 4 , consistent with the Faber‐Jackson law. Emission-line ratios indicative of the gas excitation such as [O III]/Hβ and [O III]/[O II] are statistically smaller for Seyferts with significant star formation, implying that ionization by massive stars is responsible for a substantial and sometimes even a dominant fraction of the Hβ and [O II] fluxes. We use our models to constrain the maximum fraction of the ionizing power that can be generated by a hidden active galactic nucleus (AGN). We correlate this fraction with classical indic...
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Round-ups are the summaries of handpicked papers around trending topics published every week. These would enable you to scan through a collection of papers and decide if the paper is relevant to you before actually investing time into reading it.
Climate change Research Articles published between Jun 20, 2022 to Jun 26, 2022
Jun 27, 2022
Articles Included: 2
One eighth of the bird species in the world is considered globally threatened; the avifauna of Iraq comprises 409 species and is considered as the maj...Read More